I have thought of another way to present this problem.
One that might convince you.
I can provide screen shots, but that takes up bandwidth. I have fios, but your millage may vary.
Ok, lets start loading ubuntu. Eventually it gets to the partitioner.
The partitioner says something like, 'do you want to use the whole drive'`. It shows 80G
But it will not allow me to use more than about 75G.
This is using the same measuring tool, akin to using the same yardstick.
Also Bios said that the drive was a WDC WD800BB-750KAO
Taking the core WD800BB I find a link that does this:
It is an 80G drive. And this is a mystery, a harder problem than you might initially suspect.
I had a similar problem with some of the utils on Ultimate Boot 2007, they would show but not delete the extra partitions.